Tuberculosis blood tests should be banned, says WHO

Blood testing kits used to detect active tuberculosis are unreliable and should be banned, the World Health Organization warned Wednesday.

The tuberculosis tests, widely used in developing countries, are dangerous because they both over-diagnose and miss true cases of the bacterial disease, the international group said in a news release.

The WHO’s position is based on a review of nearly 100 studies of the diagnostic tests for both tuberculosis of the lungs and of other organs. The blood tests look for antibodies the body would produce against the bacterium Mycobacterium tuberculosis, bu the results from these tests are often inconsistent, the WHO review found. The group is still reviewing blood tests for inactive (latent) tuberculosis infection.

Such commercial blood tests aren’t approved by the FDA but are sold in other parts of the world, in particular where regulatory agencies are weak, the policy statement notes. More than a million of these tests, which can cost up to $30, are carried out every year.

About one-third of the world is infected with the tuberculosis bacterium, but not every person is contagious. The disease is spread when someone with an active lung infection coughs, sneezes or otherwise propels germs through the air. The WHO estimates 1.7 million people died of tuberculosis in 2009.